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Unformatted text preview: Chapter 3 Biological Molecules Aside from water, most biologically related molecules contain carbon.---Organic molecules are molecules containing carbon. Carbon atoms are the most versatile building blocks of molecules Carbon has a valence of 4. Can bind to 2, 3, or 4 other atoms. Another factor which leads to the versatility of organic molecules is the attachment of functional groups (see table 3-1)---Functional groups are small characteristic groups of atoms which are frequently bonded to the carbon skeleton of organic molecules. Table 3.1 Functional groups: • Have specific chemical and physical properties. • Are regions of organic molecules which are frequently chemically reactive. • Behave consistently from one organic molecule to another. • Can determine the chemical properties of the organic molecule in which they are located. 1) Hydrogen Group (-H)---Hydrogen group is a functional group of a hydrogen atom bonded to a carbon atom (of the carbon skeleton).-Is either a polar group or a non-polar group depending on the atom to which the hydrogen is attached.-Involved in condensation (dehydration) and hydrolysis reactions 2) Hydroxyl Group (-OH)---Hydroxyl group is a functional group of a hydrogen atom bonded to an oxygen atom which is bonded to a carbon atom (of the carbon skeleton).-Is a polar group-Involved in condensation (dehydration) and hydrolysis reactions O H H O HO OH HO OH OH HO Dehydration synthesis Page 39 3)Carboxyl Group (-COOH)---Carboxyl group is a functional group in which a carbon atom is double bonded to an oxygen atom (like a carbonyl) and is also single bonded to the oxygen atom of a hydroxyl group.-Since this group can donate a proton, it is an acid-Involved in peptide bonds 4)Amino Groups (-NH2)---Amino groups are functional groups in which two hydrogen atoms are bonded to a nitrogen atom which is bonded to a carbon atom (of the carbon skeleton).-Acts as a weak base (similar to ammonia)-Involved in peptide bonds amino acid amino group amino group carboxyl group amino acid carboxyl group 5)Phosphate Groups (-PO 4 )---Phosphate group is a functional group which is the dissociated form of phosphoric acid (H 3 PO 4 ) 5)Phosphate Groups (-PO 4 )-Acts as an acid because of the ability to donate protons.-Links nucleotides-Important in cellular energy storage and energy transfer. Example: ATP 6) Methyl Groups (-CH 3 )---Methyl group is a functional group which consists of three hydrogen atoms bonded to a carbon atom. -Is a non-polar group.-Makes the molecule more hydrophobic SYNTHESIZING ORGANIC MOLECULES: A MODULAR APPROACH Biological molecules are often put together in subunits , or modules, called monomers .---the simple molecules condensed into more complex ones---monomers into polymers---Polymer are chains of similar building blocks or monomers....
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